RESIN COMPOSITION

Abstract: A resin composition which is well balanced among moldability, heat-resistance and mechanical strength and comprises an aromatic polyamideimide resin (A) and a polyester resin (B), a polyphenylene sulfide resin (C) or a resin (D) capable of forming an anisotropic molten phase. The resin component (A) is composed of 5-95 mol % of repeating units represented by general formula (1) and 95-5 mol % of at least either repeating units represented by general formula (2) or ones represented by general formula (3), and is produced by the process which comprises polymerizing an aromatic tricarboxylic acid anhydride, at least either aromatic or aliphatic dicarboxylic acid, and an isocyanate compound in two or more steps, wherein the reaction in the first step is conducted in the temperature range of 50-110 °C and those in the second and subsequent steps are conducted in the temperature range of over 110 °C to 200 °C. In said formulae Ar represents a trivalent aromatic group, Ar₁ represents a divalent aromatic group, R₁ represents a divalent aliphatic group, and R represents a divalent aromatic or aliphatic group.

Description: This invention relates to a novel resin composition which is excellent in heat resistance, mechanical strengths and melt moldability. Aromatic polyamideimide resins are plastic materials excellent in heat resistance, mechanical strengths, electrical properties and chemical resistance, and have been so far used as varnishes, films, etc. An aromatic polyamideimide resin is produced typically by a method in which an aromatic tricarboxylic acid anhydride and a diisocyanate are reacted in a solvent or a method in which an aromatic tricarboxylic acid anhydride halide and a diamine are reacted in a solvent. However, the polyamideimide resins produced by these methods are, though suitably used in the preparation of varnishes, cast films, etc., not suitable for use in melt molding including injection molding because of its inferior melt moldability. In the specification of U.S. Patent No. 4,313,868, there is proposed a copolyamideimide for use in injection-molding, said copolyamideimide having the following recurring polyamideimide unit (I) and recurring polyamide unit (II), wherein R is a divalent aromatic hydrocarbon radical having about 6 to about 20 carbon atoms or a divalent hydrocarbon which is bound to a group selected from the group consisting of -O-, methylene, -CO- and -SO 2 -either directly or via a stable linkage, and X is a divalent aromatic radical, the unit (I):unit (II) molar ratio being 80:20 to 20:80. Compared to a polyamideimide resin free of the recurring unit (II), the above copolyamideimide has improved melt moldability, but a flow starting time in melt-molding of the copolyamideimide is close to a decomposition temperature in melting of the copolyamideimide, so that good molding of the copolyamideimide remains unachieved. Japanese Laid-open Patent Application (Kokai) No. 59-8,755 (8,755/1984) proposes an abrasion-resistant resin molding material comprising an intimate mixture of (a) 30 to 90 % by weight of a polyamideimide resin, (b) 10 to 70 % by weight of graphite and/or molybdenum disulfide, and (c) 0 to 30 % by weight of at least one member selected from a polyphenylene sulfide resin, a polyamide resin and an aromatic polyester resin which have better flowability than the polyamideimide resin. The above polyamideimide resin (a) is an aromatic polymer which has 30 to 100 mol% of a recurring unit represented by the formula (III), and which may have less than 70 mol% of a polyamide unit represented by the formula (IV). Ar in the formula (III) is a trivalent aromatic group containing at least one 6-membered carbon ring. R in the formulas (III) and (IV) is a divalent aromatic group and/or a divalent aliphatic group. Ar' in the formula (IV) is a divalent aromatic or aliphatic group containing at least one 6-membered carbon ring. In this document, it is described that at least one member of the resin (c) selected from the polyphenylene sulfide resin, the polyamide resin and the aromatic polyester resin is contained in the molding material as a good fluidity imparting agent. However, said document neither discloses nor suggests this invention. It is desirable to provide a novel resin composition containing a polyamideimide resin and a polyester resin as main components. It is yet further desirable to provide a resin composition which has a good balance among a heat resistance, mechanical properties and a flowability. That is, in accordance with this invention, there is first provided a resin composition which comprises: (A) an aromatic copolyamideimide containing (i) 5 to 95 mol% of a recurring unit represented by the formula (1) and (ii) 5 to 95 mol% of the total a recurring unit represented by the formula (2) and/or a recurring unit represented by the formula (3), provided that the total amount of these three recurring units is 100 mol%, wherein Ar in the formula (1) denotes a trivalent aromatic group containing at least one 6-membered carbon ring, Ar 1 in the formula (2) denotes a divalent aromatic group containing at least one 6-membered carbon ring, R 1 in the formula (3) denotes a divalent aliphatic group, and R in the formulas (1), (2) and (3) denotes a divalent aromatic or aliphatic group, and (B) a polyester resin which is a crystlline aromatic polyester obtainable from an aromatice dicarboxylic acid or a derivative therof and a dihydric alcohol as raw materials, the weight ratio of the aromatic copolyamideimide (A) and the polyester resin (B) ((A)/(B)) being 95/5 to 5/95; the aromatic copolyamideimide (A) being prepared by polymerizing an aromatic tricarboxylic acid anhydride and at least one of an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid with a diisocyanate compound in a plurality of steps such that in the first step the polymerization reaction is conducted in a temperature range of 50 to 110°C and in the second and any subsequent steps the polymerization reaction is conducted in a temperature range of higher than 110°C but not higher than 200°C; and the aromatic copolyamideimide (A) having a reduced viscosity (measured in a dimethylformamide solvent at 30°C in a concentration of 1g/dl) of 0.1 to 1.0 dl/g. This invention will be described in more detail below, which will make clear the, advantages and effects of this invention. The aromatic copolyamideimide (A) used in the resin composition of this invention is composed of the recurring unit represented by the above formula (1) (hereinafter referred to at times as a "recurring unit (1)) and at least any one of the recurring unit represented by the above formula (2)(hereinafter referred to at times as a "recurring unit (2)") and the recurring unit represented by the above formula (3) (hereinafter referred to at times as a "recurring unit (3)"). The total content of the recurring units (1), (2) and (3) is 100 mol%, and the content of recurring units (1) is 5 to 95 mol%, and the content of the recurring unit (2) and/or the recurring unit (3) is 5 to 95 mol%. Preferably, the content of the recurring unit (1) is 10 to 70 mol%, and the content of the recurring unit (2) and/or the recurring unit (3) is 30 to 90 mol%. More preferably, the content of the recurring unit (1) is 10 to 50 mol%, and the content of the recurring unit (2) and/or the recurring unit (3) is 50 to 90 mol%. Especially preferably, the content of the recurring unit (1) is 10 to 30 mol%, and the content of the recurring unit (2) and/or the recurring unit (3) is 70 to 90 mol%. Further, it is preferred that the aromatic copolyamideimide contains at least 1 mol% of each of the recurring unit (2) and the recurring unit (3). In the formula (1), Ar is a trivalent aromatic group containing at least one 6-membered carbon ring, preferably a trivalent aromatic group containing 6 to 13 carbon atoms. Specific examples of Ar are as follows. Of these, the following is a preferable group. In the formulas (1), (2) and (3), R is a divalent aromatic group, preferably a divalent aromatic group having 6 to 15 carbon atoms, or a divalent aliphatic group, preferably an aliphatic group having 2 to 12 carbon atoms. R's in the formulas (1), (2) and (3) can be the same or different. Specific examples of R are the following divalent groups. Preferable examples of these groups are the following groups. Especially preferable examples of these are the following groups. Most preferable examples of R are the following groups. Ar 1 in the formula (2) is a divalent aromatic group containing at least one 6-membered carbon ring, preferably a divalent aromatic group having 6 to 13 carbon atoms. Specific examples of Ar 1 are the following divalent groups. Preferable examples of these are the following groups. Especially preferable examples of Ar 1 are the following groups. R 1 in the formula (3) is a divalent aliphatic group, preferably a divalent aliphatic group having 2 to 20 carbon atoms. A specific example of R 1 is a linear alkylene group represented by the formula -(CH 2 ) m - wherein m is an integer of 2 to 20. A linear alkylene group wherein m is an integer of 4 to 12 is a preferable example. A degree of polymerization of the aromatic copolyamideimide (A) is, when expressed in terms of a reduced viscosity measured in a dimethylformamide solvent at 30°C in a concentration of 1 g/dl, 0.1 to 1.0 dl/g, preferably 0.2 to 0.7 dl/g. The aromatic copolyamideimide (A) may be a random copolymer in which the recurring units (1) and (2) and/or (3) are substantially randomly arranged, an alternating copolymer in which these units are alternately arranged, or a block copolymer in which these units are individually bound to form block chains and these block chains are bound to one another. The aromatic copolyamideimide (A) can be produced by any of the following methods (a), (b) and (c). (a) a method in which an aromatic tricarboxylic acid anhydride and an aromatic dicarboxylic acid and/or an aliphatic dicarboxylic acid are reacted with a diisocyanate compound in an amide group-containing solvent or an amide group-free solvent to produce the copolymer (A). (b) a method in which an aromatic tricarboxylic acid anhydride and an aromatic dicarboxylic acid and/or an aliphatic dicarboxylic acid are reacted with a diamine compound in the presence of a polycondensation catalyst such as phosphoric acid or a phosphorous acid ester. Method described (b) is complicated by the need for heating to high temperatures to form the imide ring. Accordingly, the method described in (a) is most preferred to form the copolyamideimide of the composition of the invention, and it forms the basis of the process of the invention. Method (a) will therefore be explained below. The aromatic tricarboxylic acid anhydride, the aromatic dicarboxylic acid, the aliphatic dicarboxylic acid and the diisocyanate compound which are raw materials used to produce the aromatic copolyamideimide (A) by the above method (a) are as follows. Aromatic tricarboxylic acid anhydride wherein Ar is as defined in the formula (1). Aromatic dicarboxylic acid wherein Ar 1 is as defined in the formula (2). Aliphatic dicarboxylic acid wherein R 1 is as defined in the formula (2). Diisocyanate compound O=C=N-R-N=C=O wherein R is as defined in the formulas (1) to (3). In the reaction, it is desirable that the amounts of the acid component (the aromatic tricarboxylic acid anhydride, the aromatic dicarboxylic acid and the aliphatic dicarboxylic acid) and the diisocyanate compound meet 0.9 < Q / P < 1.1, especially 0.99 < Q / P < 1.01 wherein Q is a molar amount of the acid component and P is a molar amount of the diisocyanate compound. The aromatic copolyamideimide (A) can be prepared by dissolving the predetermined amounts of the above raw materials in a solvent and subsequently conducting the polymerization reaction. The temperature of the polymerization reaction is preferably 50 to 200°C, more preferably 80 to 180°C, especially preferably 80 to 170°C. In the above range of the temperature, the aromatic copolyamideimide (A) can be obtained which has a suitable degree of polymerization and does not impede a melt-moldability of the resin composition of this invention. The polymerization reaction is conducted in plural steps, preferably in two or three steps, and the temperature is elevated in each step, whereby the better aromatic copolyamideimide (A) can be produced. That is, the copolyamideimide (A) having excellent melt moldability and toughness can be produced by conducting the polymerization reaction such that the temperature range in the first step is 50 to 110°C and the temperature ranges in the second and subsequent steps are higher than 110°C but not higher than 200°C. In this manner, the polymerization reaction is conducted in plural steps, in which formation of the amide group can be terminated in the first reaction step and an imide can be formed in the subsequent reaction steps at higher temperatures. Consequently, the resulting copolymer (A) is substantially free from a complicated three-dimensional structure. Any temperatures can be set in the respective steps within the aforesaid temperature ranges. For example, within the above temperature ranges, the temperatures may be elevated or maintained constant. Further, the elevation of the temperature may be combined with the maintenance of the constant temperature. Most preferable is that the polymerization reaction is conducted by making the temperature in one step higher by 20 to 80°C than that in the preceding step and maintaining the temperature in each step constant. As the solvent in the polymerization reaction, a solvent having a solubility in the resulting polyamideimide and a polar solvent having no solubility in the polyamideimide can be used. Specific examples of the solvent having a solubility in the polyamideimide include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, dimethylsulfolane, tetramethylenesulfone, diphenylsulfone and γ-butyrolactone. Specific examples of the polar solvent having no solubility in the polyamideimide include nitrobenzene, nitrotoluene, acetonitrile, benzonitrile, acetophenone, nitromethane, dichlorobenzene and anisole. The solvent having a solubility in the polyamideimide and the solvent having no solubility in the polyamideimide may be used singly or in combination. Of the above solvents, the solvent having a solubility in the polyamideimide is preferable. The solvent is used preferably on condition that the ratio of the raw materials to the solvent is 0.1 to 4 mols/liter (raw materials/solvent). In the polymerization reaction, it is possible to use a variety of conventionally known catalysts used for forming an amide group by the reaction of an isocyanate group and a carboxyl group. In order not to impair a melt moldability and a processability of the copolymer (A), the amount of the catalyst shall be reduced to the necessary minimum. Of course, the reaction can be conducted in the absence of a catalyst. Specific examples of the catalyst include tertiary amines such as pyridine, quinoline, isoquinoline, trimethylamine, triethylamine, tributylamine, N,N-diethylamine, γ-picoline, N-methylmorpholine, N-ethylmorpholine, triethylenediamine and 1,8-diazabicyclo[5,4,0]undecene-7; and weakly acidic metal salts (heavy metal salts and alkali metal salts) such as cobal acetate, cobalt naphthenate and sodium oleate. In the polymerization reaction, it is advisable that the mixture containing the raw materials, the solvent and optionally the catalyst is substantially free from water. The amount of water present is preferably at most 500 ppm, more preferably at most 100 ppm, especially preferably at most 50 ppm. Excess water impairs a melt moldability of the copolymer (A). After the polymerization reaction, the copolymer is precipitated with alcohols such as methanol and isopropyl alcohol, ketones such as acetone and methyl ethyl ketone and aliphatic and aromatic hydrocarbons such as heptane and toluene, and successively washed, thereby recovering the aromatic copolyamideimide (A). Another method is that the aromatic copolyamideimide (A) can be recovered by distilling off the polymerization solvent. The other method is that after the solvent is distilled off to some extent, the product containing a small amount of the solvent is fed to an extruder, and the product is pelletized to recover the aromatic polyamideimide, while the solvent is removed from a vent hole provided in the extruder under reduced pressure. This method is suitable. The polyester resin (B) used in the resin composition of this invention is a thermoplastic resin having an ester linkage in the main chain of the molecule. Specific examples of the polyester resin (B) include a polycondensate obtained from a dicarboxylic acid or a derivative thereof and a dihydric alcohol. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxylphenylacetic acid, p-phenylenediacetic acid, m-phenylenediglycolic acid, p-phenylenediglycolic acid, diphenyl diacetic acid, diphenyl-p,p'-dicarboxylic acid, diphenyl ether-p,p'-dicarboxylic acid, diphenyl-m,m'-dicarboxylic acid, diphenyl-4,4'-diacetic acid, diphenylmethane-p,p'-dicarboxylic acid, diphenylethane-p,p'-dicarboxylic acid, stilbenedicarboxylic acid, diphenylbutane-p,p'-dicarboxylic acid, benzophenone-4,4'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, p-carboxyphenoxyacetic acid, p-carboxyphenoxybutyric acid, 1,2-diphenoxypropane-p,p'-dicarboxylic acid, 1,3-diphenoxypropane-p,p'-dicarboxylic acid, 1,4-diphenoxybutane-p,p'-dicarboxylic acid, 1,5-diphenoxypentane-p,p'-dicarboxylic acid, 1,6-diphenoxyhexane-p,p'-dicarboxylic acid, p-(p-carboxyphenoxy)benzoic acid, 1,2-bis(2-methoxyphenoxy)-ethane-p,p'-dicarboxylic acid, and 1,3-bis(2-methoxyphenoxy)-propane-p,p'-dicarboxylic acid. Of these terephthalic acid, isophthatic acid and naphthalene-2,6-dicarboxylic acid are preferred. Examples of the dihydric alcohol include ethylene glycol, propane-1,2-diol, propane-1,3-diol, butane-1,3-diol, butane-1,4-diol, 2,2-dimethylpropane-1,3-diol, cis-2-butene-1,4-diol, trans-2-butene-1,4-diol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol, and decamethylene glycol. Preferable are ethylene glycol, propane-1,2-diol, propane-1,3-diol, butane-1,3-diol, and butane-1,4-diol. More preferable are ethylene glycol, and butane-1,4-diol. The polyester which is used in the resin composition of this invention is prepared using the above raw materials by a method known per se such as an ester interchange method, a direct esterification method or an interfacial polycondensation method. The polyester resin (B) which is used to keep a good balance of a melt moldability and a heat resistance in the resin composition of this invention is a crystalline aromatic polyester obtainable from an aromatic dicarboxylic acid or a derivative thereof and a dihydric alcohol as raw materials. Preferable examples of the aromatic polyester include polyalkylene terephthalates (in which an alkylene having 2 to 6 carbon atoms is preferable) such as polyethylene terephthalate and polybutylene terephthalate, and polyalkylene-2,6-naphthalenedicarboxylates (in which an alkylene having 2 to 6 carbon atoms is preferable) such as polyethylene-2,6-naphthalenedicarboxylate and polybutylene-2,6-naphthalenedicarboxylate. The most preferable examples of the polyester resin (B) are polyethylene terephthalate and polybutylene terephthalate. The weight average molecular weight of the polyester resin (B) is preferably at least 20,000, for example. The weight ratio of the aromatic copolyamideimide (A) and the polyester resin (B) ((A)/(B)) is 5/95 to 95/5, preferably 10/90 to 70/30, more preferably 10/90 to 65/35, most preferably at least 10/90 but less than 50/50. Such mixing ratio gives an excellent balance of a flowability and a heat resistance to the resin composition of this invention. The resin composition of the aromatic copolyamideimide (A) and the polyester resin (B) is produced by melt-kneading the respective components, and the temperature for the melt-kneading is 200 to 400°C, preferably 230 to 380°C. The melt-kneading can be carried out with an extruder, a kneader, a Banbury mixer, rolls or the like. A twin-screw extruder is preferable. The polyester resin (B) may be a polyester resin capable of forming an anisotropic molten phase or a polyester resin incapable of forming an anisotropic molten phase and capable of forming an isotropic molten phase alone. The resin composition of this invention can properly contain, as required, additives such as a filler, a pigment, a plasticizer, a stabilizer, an ultraviolet absorber, a flame retardant, and a flame retardant aid, other resins and an elastomer. Examples of the filler include mineral fillers such as glass beads, wollastonite, mica, talc, Kaolin clay, silicon dioxide, asbestos, calcium carbonate, magnesium hydroxide, silica, diatomaceous earth, graphite, carborundum and molybdenum disulfide; inorganic fibers such as a glass fiber, a milled fiber, a potassium titanate fiber, a boron fiber, a silicon carbide fiber, and fibers of metals such as brass, aluminum and zinc; organic fibers typified by a carbon fiber and an aramid fiber; and flakes of aluminum and zinc. The amount of the filler is preferably 1 to 70 % by weight based on the whole resin composition. Preferable fillers are the milled fiber, the glass fiber and the carbon fiber. These fibers treated with an epoxy-, amino- or urethane-based silane coupling agent are preferably used. Examples of the pigment include titanium oxide, zinc sulfide and zinc oxide. Typical examples of the lubricant include a mineral oil, a silicone oil, an ethylene wax, a polypropylene wax, metal stearates such as sodium stearate and lithium stearate, metal montanates such as sodium montanate, lithium montanate and zinc montanate, montanic acid amide and montanic acid ester. Examples of the flame retardant include phosphoric acid esters such as triphenyl phosphate and tricresyl phosphate; brominated compounds such as decabromobiphenyl, pentabromotoluene, decabromobiphenyl ether, hexabromobenzene, brominated polystyrene, a brominated epoxy resin and a brominated phenoxy resin; nitrogen-containing compounds such as melamine derivatives; and nitrogen-containing phosphorus compounds such as a cyclic phosphagen compound and a phosphagen polymer. The flame retardant aid may be used. Examples of the flame retardant aid include compounds of antimony, boron, zinc and iron. Other additives include a stabilizer such as a phenol having steric hindrance or a phosphite compound; and an ultraviolet absorber such as an oxalic acid diamide compound or an amine compound having steric hindrance. Examples of the other resin that can be mixed include epoxy resins and phenoxy resins produced from epichlorohydrin and a dihydric phenol such as 2,2-bis(4-hydroxyphenyl)propane; aliphatic and aromatic crystalline polyamides such as nylon-6, nylon-10, nylon-12, nylon-6,6, nylon-MXD,6, nylon 4,6, nylon-6,T and nylon-6,I; aliphatic and aromatic noncrystalline polyamides; polycarbonates produced by reacting at least one dihydric phenol selected from hydroquinone, resorcin, 4,4'-dihydroxydiphenyl, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl) ether, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl) ketone and 4-hydroxyphenyl-3-hydroxyphenyl ketone with phosgene, diphenyl carbonate or dimethyl carbonate; polyester carbonates produced by the reaction of a dihydric phenol with phosgene, diphenyl carbonate or dimethyl carbonate and a dicarboxylic acid or its derivatives; polyphenylene ether obtained by oxidation and coupling polymerization of 2,6-dimethylphenol; and aromatic resins such as polysulfone, polyether sulfone, polyether imide, polythioether ketone, polyether ketone and polyether ether ketone. Examples of the elastomer include a polyester elastomer typified by a block copolymer of a high-melting hard segment composed mainly of an alkylene terephthalate unit comprising the above dihydric alcohol and terephthalic acid and a soft segment composed of an aliphatic polyester produced from polyether glycol such as poly(ethylene oxide) glycol or poly(propylene oxide) glycol or an aliphatic dicarboxylic acid and a dihydric alcohol (its typical products are PELPRENE made by Toyobo Co., Ltd., and HYTREL made by E. I. du Pont de Nemours & Co.); a polyamide elastomer typified by a block copolymer of a hard segment such as nylon 11 or nylon 12 and a soft segment such as a polyether or a polyester (its typical product is GRILAMID made by EMS CHEMIE); low-density, high-density, ultrahigh-molecular-weight and linear low-density polyethylenes; polypropylene; an EP elastomer which is a copolymer of ethylene and propylene; an EPDM elastomer which is a copolymer of ethylene, propylene and a non-conjugated diene such as rbornene, cyclopentadiene or 1,4-hexadiene; a copolymer elastomer of an α-olefin such as ethylene, propylene or butene-1 and an α,β-unsaturated acid glycidyl ester such as glycidyl acrylate or glycidyl methacrylate; a copolymer elastomer of an α-olefin such as ethylene, propylene or butene-1 and an unsaturated ester such as vinyl acetate, vinyl propionate, methyl acrylate or methyl methacrylate; the above polyethylene, polypropylene, EP, EPDM and α-olefin copolymer elastomer which are graft-modified with an α,β-unsaturated dicarboxylic acid anhydride such as maleic anhydride or an α,β-unsaturated acid glycidyl ester such as glycidyl methacrylate; an A-B-A, A-B type elastomeric block copolymer comprising a block A composed of a polymer chain of a vinyl aromatic compound such as styrene and a block B composed of a polymer chain of a diene component such as butadiene or isoprene; an A-B-A, A-B type elastomeric block copolymer obtained by hydrogenating the block B, an A-B-A, A-B type elastomeric block copolymer graft-modified with an α,β-unsaturated dicarboxylic acid anhydride such as maleic anhydride or an α,β-unsaturated acid glycidyl ester such as glycidyl methacrylate, and an A-B-A, A-B type elastomeric block copolymer obtained by the same graft-modification and hydrogenation of the block B; and a polysulfide rubber and a silicone rubber. The resin composition of this invention which has been detailed above has a good balance of a flowability, a heat resistance and mechanical strengths even though the resin composition is a combination of the aromatic copolyamideimide (A) and the polyester resin (B). That is, although a heat resistance and mechanical strengths inherent in the aromatic copolyamideimide (A) are somewhat sacrificed, a flowability which the resin (A) essentially lacks is improved by mixing with the other resin, making the resin (A) melt-moldable. In consequence, the resin composition of this invention has a good balance of properties, and can usefully be applied where heat resistance is required, such as electrical and electronic parts, parts of automobile engines and the like. Especially, it can be mentioned that the resin composition of this invention has an excellent heat resistance even when the amount of the imide structure contained in aromatic copolyamideimide (A) is small. This invention will be specifically illustrated by the following Examples. Synthesis Example 1: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into a 5-liter reactor equipped with a stirrer, a thermometer and a reflux condenser having a drying tube whose top was filled with calcium chloride. To this were added 155.5 g (14 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 304.1 g (36 mol% on the same basis) of adipic acid, and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. When trimellitic anhydride and adipic acid were added, the water content in the reaction system was 30 ppm. First, the temperature of the contents was elevated from room temperature to 100°C over a period of 20 minutes, and the polymerization was conducted at this temperature for 4 hours. Then, the temperature was elevated to 115°C over a period of 15 minutes. While this temperature was maintained, the polymerization was continued for 4 hours, and further conducted at 160°C for 2 hours. After the polymerization was over, the polymer solution was added dropwise to methanol in a volume which was twice that of N-methylpyrrolidone under vigorous stirring. The precipitated polymer was separated by suction filtration, further redispersed in methanol for full washing, separated by filtration, and dried under reduced pressure at 200°C for 10 hours to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 10 g/dl) at 30°C, and then found to be 0.38 dl/g. Further, a glass transition temperature of the polyamideimide powder was measured by differential scanning calorimetry (DSC) method. The results are shown in Table 1 together with the results of other Synthesis Examples. Synthesis Example 2: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into a 5-liter reactor equipped with a stirrer, a thermometer and a reflux condenser having a drying tube whose top was filled with calcium chloride. Trimellitic anhydride (222.1 g: 20 mol% based on the total molar amount of all the monomer components) and 253.2 g (30 mol% on the same basis) of adipic acid were charged into a 5-liter reactor equipped with a stirrer, a thermometer and a drying tube whose top was filled with calcium chloride. Then, 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate was added. Subsequently, in the same manner as in Synthesis Example 2, the polymerization and the treatment were conducted to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.36 dl/g. Synthesis Example 3: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm was charged into the same reactor as that used in Synthesis Example 1. To this were added 333.1 g (30 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 168.9 g (20 mol% on the same basis) of adipic acid and 503.3 g (50 mol % on the same basis) of 2,4-toluylene diisocyanate. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 1 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.33 dl/g. Synthesis Example 4: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged in the same reactor as that used in Synthesis Example 1. To this were added 444.2 g (40 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 84.4 g (10 mol% on the same basis) of adipic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 1 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.32 dl/g. Synthesis Example 5: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged in the same reactor as that used in Synthesis Example 1. To this were added 555.3 g (50 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. When trimellitic anhydride was added, the water content in the reaction system was 25 ppm. When trimellitic anhydride was added, the water content in the reaction system was 25 ppm. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 1 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.30 dl/g. Synthesis Example 6: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 1. To this were added 422.3 g (50 mol% based on the total molar amount of all the monomer components) of adipic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. When adipic acid was added, the water content in the reaction system was 50 ppm. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 1 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.35 dl/g. The compositions and the properties of the polymers synthesized in Synthesis Examples 1 to 6 are shown in Table 1. Example 1: Fifty (50) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 1 and 50 % by weight of polybutylene terephthalate (hereinafter abbreviated as "PBT", Nll00C: a trade name for a product made by Mitsubishi Rayon Company Limited) were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The resulting pellets were injection molded to form test pieces having a thickness of 1/8 inch. The test pieces were measured for a heat deformation temperature at a stress of 18.6 kg/cm 2 to evaluate a heat resistance and for a flexural strength to evaluate a mechanical strength. Further, regarding a melt moldability, a melt flow value was measured at 270°C under a stress of 30 kg/cm 2 by a Koka type flow tester (capillary rheometer). The results are shown in Table 2. Examples 2 to 4: Example 1 was repeated except that the aromatic copolyamideimide in Example 1 was replaced with the aromatic copolyamideimides in Synthesis Examples 2 to 4. The results are shown in Table 2. Comparative Examples 1 and 2: Example 1 was repeated except that the aromatic copolyamideimide in Example 1 was replaced with the aromatic copolyamideimides or the aromatic polyamides in Synthesis Examples 5 and 6. The results are shown in Table 2. Example 5: Forty (40) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 2, 50 % by weight of PBT and 10 % by weight of bisphenol A polycarbonate (hereinafter abbreviated as "PC"; IUPILON E2000, a trade name for a product made by Mitsubishi Gas Chemical Company., Inc.) were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The obtained pellets were injection-molded to form test pieces having a thickness of 1/8 inch. The test pieces were measured for a heat deformation temperature at a stress of 18.6 kg/cm 2 to evaluate a heat resistance and for a flexural strength to evaluate a mechanical strength. Further, regarding a melt moldability, a melt flow value was measured at 270°C under a stress of 60 kg/cm 2 by a capillary rheometer. The results are shown in Table 3. Comparative Example 3: Example 5 was repeated except that the aromatic copolyamideimide in Example 5 was replaced with the aromatic copolyamideimide in Synthesis Example 5. The results are shown in Table 3. Example 6: Twenty (20) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 2, 30 % by weight of polyethylene terephthalate (hereinafter abbreviated as "PET"; RT543, a trade name for a product made by Nippon Unipet Co., Ltd.), 10 % by weight of PC and further 40 % by weight of glass fibers (hereinafter referred to as "glass fibers" or "GF"; 03JAFT540, a trade name for chopped strands made by Asahi Fiber Glass Co., Ltd) were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The obtained pellets were injection-molded in the same manner as in Example 5 to form test pieces. The test pieces were measured for a heat deformation temperature, a flexural strength and further a melt flow value in the same manner as in Example 5. The results are shown in Table 3. Comparative Example 4: Example 6 was repeated except that the aromatic copolyamideimide in Example 6 was replaced with the aromatic copolyamideimide in Synthesis Example 5. The results are shown in Table 3. Example 7: Thirty (30) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 2, 30 % by weight of PBT and 40 % by weight of glass fibers were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The obtained pellets were injection-molded in the same manner as in Example 5 to form test pieces. The test pieces were measured for a heat deformation temperature, a flexural strength and further a melt flow value in the same manner as in Example 5. The results are shown in Table 3. Comparative Example 5: Example 7 was repeated except that the aromatic copolyamideimide in Example 7 was replaced with the aromatic copolyamideimide in Synthesis Example 5. The results are shown in Table 3. Example 8: Example 7 was repeated except that PBT in Example 7 was replaced with PET. The results are shown in Table 3. Example 9: Example 8 was repeated except that the aromatic copolyamideimide in Example 8 was replaced with the aromatic copolyamideimide in Synthesis Example 1. The results are shown in Table 3. Comparative Example 6: Example 9 was repeated except that the aromatic copolyamideimide in Example 9 was replaced with the aromatic copolyamideimide in Synthesis Example 5. The results are shown in Table 3. Synthesis Example Composition of acid component Diisocyanate Glass transition point (°C) TMA (mole%) ADA (mole%) TDI (mole%) 1 14 36 50 170 2 20 30 50 180 3 30 20 50 220 4 40 10 50 285 5 50 0 50 326 6 0 50 50 155 TMA; trimellitic anhydride ADA; adipic acid TDI; 2,4-toluylene diisocyanate Kind of amideimide (wt.%) Kind of polyester (wt.%) Heat deformation temp. (°C) Flexural strength (MPa) Melt-flow value (cc/sec) Ex. 1 Synthesis Example 1 50 PBT 50 178 87 0.07 Ex. 2 Synthesis Example 2 50 PBT 50 186 84 0.08 Ex. 3 Synthesis Example 3 50 PBT 50 180 80 0.10 Ex. 4 Synthesis Example 4 50 PBT 50 180 75 0.11 Comp. Ex. 1 Synthesis Example 5 50 PBT 50 180 48 0.13 Comp. Ex. 2 Synthesis Examle 6 50 PBT 50 159 43 0.11 Kind of amideimide (wt.%) Kind of other component(s) Kind of polyester component Heat deformation temp. (°C) Flexural strength (MPa) Melt-flow value (cc/sec Ex. 5 Synthesis Example 2 40 PBT 50 PC 10 167 90 0.22 Ex. 6 Synthesis Example 2 20 PET 30 PC/GF 10/40 210 168 0.24 Ex. 7 Synthesis Example 2 30 PBT 30 GF 40 208 147 0.20 Ex. 8 Synthesis Example 2 30 PET 30 GF 40 220 170 0.31 Ex. 9 Synthesis Example 1 30 PET 30 GF 40 220 172 0.30 Comp. Ex. 3 Synthesis Example 5 40 PBT 50 PC 10 163 58 0.22 Comp. Ex. 4 Synthesis Example 5 20 PET 30 PC/GF 10/40 203 130 0.25 Comp. Ex. 5 Synthesis Example 5 30 PBT 30 GF 40 205 120 0.19 Comp. Ex. 6 Synthesis Example 5 30 PET 30 GF 40 210 140 0.32 Synthesis Example 11: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into a 5-liter reactor equipped with a stirrer, a thermometer and a reflux condenser having a drying tube whose top was filled with calcium chloride. To this were added 155.5 g (14 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 345.7 g (36 mol% on the same basis) of isophthalic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. When trimellitic anhydride and isophthalic acid were added, the water content in the reaction system was 30 ppm. First, the temperature of the contents was elevated from room temperature to 100°C over a period of 20 minutes, and the polymerization was conducted at this temperature for 4 hours. Then, the temperature was elevated to 115°C over a period of 15 minutes. While this temperature was maintained, the polymerization was continued for 4 hours, and further conducted at 160°C for 2 hours. After the polymerization was over, the polymer solution was added dropwise to methanol in a volume which was twice that of N-methylpyrrolidone under vigorous stirring. The precipitated polymer was separated by suction filtration, further redispersed in methanol for full washing, separated by filtration, and dried under reduced pressure at 200°C for 10 hours to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.42 dl/g. Further, a glass transition temperature of the polyamideimide powder was measured by differential scanning calorimetry (DSC) method. The results are shown in Table 1 together with the results of other Synthesis Examples. Synthesis Example 12: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into a 5-liter reactor equipped with a stirrer, a thermometer and a reflux condenser having a drying tube whose top was filled with calcium chloride. Trimellitic anhydride (222.1 g: 20 mol% based on the total molar amount of all the monomer components) and 288.1 g (30 mol% on the same basis) of isophthalic acid were charged into a 5-liter reactor equipped with a stirrer, a thermometer and a reflux condenser having a drying tube whose top was filled with calcium chloride. Then, 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate was added. Subsequently, in the same manner as in Synthesis Example 1, the polymerization and the treatment were conducted to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.40 dl/g. Synthesis Example 13: Three (3) liters of N-methylpyrrolidone having a water content of 20 ppm were charged into the same reactor as that used in Synthesis Example 11. To this were added 210.6 g (20 mol% based on the total molar amount of all the monomer components) of anhydrous trimellitic acid chloride, 304.5 g (30 mol% on the same basis) of isophthalic acid chloride and then 305.4 g (50 mol% on the same basis) of m-toluylenediamine. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 11 to obtain a polyamideimide powder. The resulting polyamideimide powder was heat-treated at 250°C for 24 hours. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.26 dl/g. Synthesis Example 14: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 11. To this were added 333.1 g (30 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 192.0 g (20 mol% on the same basis) of isophthalic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 11 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.33 d/g. Synthesis Example 15: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 1. To this were added 444.2 g (40 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 96.0 g (10 mol% on the same basis) of isophthalic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 1 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.32 d/g. Synthesis Example 16: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 11. To this were added 555.3 g (50 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. When trimellitic anhydride was added, the water content in the reaction system was 25 ppm. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 11 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.30 dl/g. Synthesis Example 17: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 11. To this were added 480.1 g (50 mol% based on the total molar amount of all the monomer components) of isophthalic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. The water content in the reaction system was 50 ppm. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 1 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.30 dl/g. The compositions and the properties of the polymers formed in Synthesis Examples 11 to 17 are shown in Table 4. Example 11: Fifty (50) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 11 and 50 % by weight of PBT were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The resulting pellets were injection-molded to form test pieces having a thickness of 1/8 inch. The test pieces were measured for a heat deformation temperature at a stress of 18.6 kg/cm 2 to evaluate a heat resistance and for a flexural strength to evaluate a mechanical strength. Further, regarding a melt moldability, a melt flow value was measured at 270°C under a stress of 30 kg/cm 2 by a capillary rheometer. The results are shown in Table 5. Examples 12 to 15: Example 11 was repeated except that the aromatic copolyamideimide in Example 11 was replaced with the aromatic copolyamideimides in Synthesis Examples 12 to 15. The results are shown in Table 5. Comparative Examples 11 and 12: Example 11 was repeated except that the aromatic copolyamideimide in Example 11 was replaced with the aromatic copolyamideimides or the aromatic polyamides in Synthesis Examples 16 and 17. The results are shown in Table 5. Example 16: Forty (40) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 12, 50 % by weight of PBT and 10 % by weight of PC were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The resulting pellets were injection-molded to form test pieces having a thickness of 1/8 inch. The test pieces were measured for a heat deformation temperature at a stress of 18.6 kg/cm 2 to evaluate a heat resistance and for a flexural strength to evaluate a mechanical strength. Further, regarding a melt moldability, a melt flow value was measured at 270°C under a stress of 60 kg/cm 2 by a capillary rheometer. The results are shown in Table 6. Comparative Example 13: Example 16 was repeated except that the aromatic copolyamideimide in Example 16 was replaced with the aromatic copolyamideimide in Synthesis Example 16. The results are shown in Table 6. Example 17: Twenty (20) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 12, 30 % by weight of PET, 10 % by weight of PC and 40 % by weight of glass fibers were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The resulting pellets were injection-molded in the same manner as in Example 16 to form test pieces. The test pieces were measured for a heat deformation temperature, a flexural strength and further a melt flow value in the same manner as in Example 16. The results are shown in Table 6. Comparative Example 14: Example 17 was repeated except that the aromatic copolyamideimide in Example 17 was replaced with the aromatic copolyamideimide in Synthesis Example 16. The results are shown in Table 6. Example 18: Thirty (30) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 12, 30 % by weight of PBT and 40 % by weight of glass fibers were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The resulting pellets were injection-molded in the same manner as in Example 16 to form test pieces. The test pieces were measured for a heat deformation temperature, a flexural strength and further a melt flow value in the same manner as in Example 16. The results are shown in Table 6. Comparative Example 15: Example 18 was repeated except that the aromatic copolyamideimide in Example 18 was replaced with the aromatic copolyamideimide in Synthesis Example 16. The results are shown in Table 6. Example 19: Example 18 was repeated except that PBT in Example 18 was replaced with PET. The results are shown in Table 6. Comparative Example 16: Example 19 was repeated except that the aromatic copolyamideimide in Example 19 was replaced with the aromatic copolyamideimide in Synthesis Example 16. The results are shown in Table 6. Synthesis Example Composition of acid components Diisocyanate TDI (mole%) Glass transition point (°C) TMA (mole%) / IPA (mole%) 11 14/36 50 273 12 20/30 50 290 13 (acid chloride) (20/30) (m-TDA) (50) 290 14 30/20 50 305 15 40/10 50 310 16 50/ 0 50 326 17 0/50 50 260 TMA; trimellitic anhydride IPA; isophthalic acid TDI; 2,4-toluylene diisocyanate m-TDA; m-toluylenediamine acid chloride; anhydrous trimellitic acid chloride/isophthalic acid dichloride Kind of amideimide (wt.%) Kind of polyester (wt.%) Heat deformation temp. (°C) Flexural strength (MPa) Melt-flow value (cc/sec) Ex. 11 Synthesis Example 11 50 PBT 50 197 93 0.09 Ex. 12 Synthesis Example 12 50 PBT 50 200 91 0.10 Ex. 13 Synthesis Example 13 50 PBT 50 200 90 0.12 Ex. 14 Synthesis Example 14 50 PBT 50 182 78 0.11 Ex. 15 Synthesis Example 15 50 PBT 50 182 65 0.10 Comp. Ex. 11 Synthesis Example 16 50 PBT 50 180 48 0.13 Comp. Ex. 12 Synthesis Example 17 50 PBT 50 192 43 0.11 Kind of amideimide (wt.%) Kind of other component(s) (wt.%) Kind of polyester (wt.%) Heat deformation temp. (°C) Flexural strength (MPa) Melt-flow value (cc/sec) Ex. 15 Synthesis Example 12 40 PBT 50 PC 10 167 90 0.22 Ex. 16 Synthesis Example 12 20 PET 30 PC/GF 10/40 210 168 0.24 Ex. 17 Synthesis Example 12 30 PBT 30 GF 40 208 147 0.20 Ex. 18 Synthesis Example 12 30 PET 30 GF 40 220 170 0.31 Ex. 19 Synthesis Example 11 30 PET 30 GF 40 220 172 0.30 Comp. Ex. 13 Synthesis Example 15 40 PBT 50 PC 10 163 58 0.22 Comp. Ex. 14 Synthesis Example 15 20 PET 30 PC/GF 10/40 203 130 0.25 Comp. Ex. 15 Synthesis Example 15 30 PBT 30 GF 40 205 120 0.19 Comp. Ex. 16 Synthesis Example 15 30 PET 30 GF 40 210 140 0.32 Synthesis Example 21: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into a 5-liter reactor equipped with a stirrer, a thermometer and a reflux condenser having a drying tube whose top was filled with calcium chloride. To this were added 222.1 g (20 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 240.1 g (25 mol% on the same basis) of isophthalic acid, 42.2 g (5 mol% on the same basis) of adipic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. When trimellitic anhydride, isophthalic acid and adipic acid were added, the water content in the reaction system was 30 ppm. First, the temperature of the contents was elevated from room temperature to 100°C over a period of 20 minutes, and polymerization was conducted at this temperature for 4 hours. Subsequently, the temperature was elevated to 115°C over a period of 15 minutes. While maintaining this temperature, the polymerization was continued for 4 hours, and further conducted at 160°C for 2 hours. After the polymerization was over, the polymer solution was added dropwise to methanol in a volume which was twice that of N-methylpyrrolidone under vigorous stirring. The precipitated polymer was separated by suction filtration, further redispersed in methanol for full washing, then separated by filtration and dried under reduced pressure at 200°C for 10 hours to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.43 dl/g. A glass transition temperature of the polyamideimide powder was measured by differential scanning calorimetry (DSC) method. The results are shown in Table 7 together with those in other Synthesis Examples. Synthesis Example 22: Three (3) liters of N-methylpyrrolidone having a water content of 20 ppm were charged into a 5-liter reactor equipped with a stirrer, a thermometer and a reflux condenser having a drying tube whose top was filled with calcium chloride. Anhydrous trimellitic acid chloride (210.6 g: 20 mol% based on the total molar amount of all the monomer components), 253.8 g (25 mol% on the same basis) of isophthalic acid dichloride and 45.8 g (5 mol% on the same basis) of adipic acid dichloride were charged into a 5-liter reactor equipped with a stirrer, a thermometer and a reflux condenser having a drying tube whose top was filled with calcium chloride. Then, 305.4 g (50 mol% on the same basis) of m-toluylenediamine was added. First, the polymerization was conducted from room temperature to 40°C for 15 hours. Thereafter, the temperature was elevated to 150°C. While maintaining this temperature, the polymerization was continued for 7 hours. After the polymerization was over, the polymer solution was double diluted with the addition of N-methylpyrrolidone, and the diluted solution was added to methanol in a volume which was twice that of N-methylpyrrolidone under vigorous stirring. The precipitated polymer was separated by suction filtration, further redispersed in methanol for full washing, then separated by filtration and dried under reduced pressure at 200°C to obtain a polyamideimide powder. The obtained polyamideimide powder was heat-treated at 250°C for 24 hours. A reduced viscosity of the resulting polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.28 dl/g. Synthesis Example 23: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 21. To this were added 222.1 g (20 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 192.1 g (20 mol% on the same basis) of isophthalic acid, 84.4 g (10 mol% on the same basis) of adipic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 21 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.40 dl/g. Synthesis Example 24: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 21. To this were added 222.1 g (20 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 96.0 g (10 mol% on the same basis) of isophthalic acid, 168.9 g (20 mol% on the same basis) of adipic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 21 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.36 dl/g. Synthesis Example 25: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 21. To this were added 138.8 g (12.5 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 288.1 g (30 mol% on the same basis) of isophthalic acid, 63.3 g (7.5 mol% on the same basis) of adipic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 21 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.39 dl/g. Synthesis Example 26: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 21. To this were added 55.3 g (5 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 336.1 g (35 mol% on the same basis) of isophthalic acid, 84.4 g (10 mol% on the same basis) of adipic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 21 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.36 dl/g. Synthesis Example 27: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 21. To this were added 333.1 g (30 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 144.0 g (15 mol% on the same basis) of isophthalic acid, 42.2 g (5 mol% on the same basis) of adipic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 21 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.35 dl/g. Synthesis Example 28: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 21. To this were added 444.2 g (40 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride, 48.0 g (5 mol% on the same basis) of isophthalic acid, 42.2 g (5 mol% on the same basis) of adipic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 21 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.35 dl/g. Synthesis Example 29: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged in the same reactor as that used in Synthesis Example 21. To this were added 555.3 g (50 mol% based on the total molar amount of all the monomer components) of trimellitic anhydride and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. When trimellitic anhydride was added, the water content in the reaction system was 25 ppm. First, the temperature of the contents was elevated from room temperature to 90°C over a period of 20 minutes, and the polymerization was conducted at this temperature for 70 minutes. Subsequently, the temperature was elevated to 115°C over a period of 15 minutes. While maintaining this temperature, the polymerization was continued for 4 hours. After the polymerization was over, the polymer solution was added dropwise to methanol in a volume which was twice that of N-methylpyrrolidone under vigorous stirring. The precipitated polymer was separated by suction filtration, further redispersed in methanol for full washing, then separated by filtration, and dried under reduced pressure at 200°C for 15 hours to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.30 dl/g. Synthesis Example 30: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 21. To this were added 480.1 g (50 mol% based on the total molar amount of all the monomer components) of isophthalic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. When isophthalic acid was added, the water content in the reaction system was 50 ppm. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.30 dl/g. Synthesis Example 31: Three (3) liters of N-methylpyrrolidone having a water content of 15 ppm were charged into the same reactor as that used in Synthesis Example 21. To this were added 422.3 g (50 mol% based on the total molar amount of all the monomer components) of adipic acid and then 503.3 g (50 mol% on the same basis) of 2,4-toluylene diisocyanate. When adipic acid was added, the water content in the reaction system was 50 ppm. Subsequently, the polymerization and the treatment were conducted in the same manner as in Synthesis Example 1 to obtain a polyamideimide powder. A reduced viscosity of the polyamideimide powder was measured in a dimethylformamide solution (concentration 1.0 g/dl) at 30°C, and then found to be 0.35 dl/g. The compositions and the properties of the polymers formed in said Synthesis Examples 21 to 31 are shown in Table 7. Example 21: Fifty (50) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 21 and 50 % by weight of PBT were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The obtained pellets were injection-molded to form test pieces having a thickness of 1/8 inch. The test pieces were measured for a heat deformation temperature at a stress of 18.6 kg/cm 2 to evaluate a heat resistance and for a flexural strength to evaluate a mechanical strength. Further, regarding a melt moldability, a melt flow value was measured at 270°C under a stress of 30 kg/cm 2 by a capillary rheometer. The results are shown in Table 8. Examples 22 to 28: Example 21 was repeated except that the aromatic copolyamideimide in Example 21 was replaced with the aromatic copolyamideimides in Synthesis Examples 22 to 28. The results are shown in Table 8. Comparative Examples 21 to 23: Example 21 was repeated except that the aromatic copolyamideimides in Example 21 was replaced with the aromatic copolyamideimide or the aromatic polyamides in Synthesis Examples 29 to 31. The results are shown in Table 8. Example 29: Forty (40) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 23, 50 % by weight of PBT and 10 % by weight of PC were melt-kneaded at 280°C and pelletized with a twin-screw extruder to form pellets. The obtained pellets were injection-molded to give test pieces having a thickness of 1/8 inch. The test pieces were measured for a heat deformation temperature at a stress of 18.6 kg/cm 2 to evaluate a heat resistance and for a flexural strength to evaluate a mechanical strength. Further, regarding a melt moldability, a melt flow value was measured at 270°C under a stress of 60 kg/cm 2 by a capillary rheometer. The results are shown in Table 9. Comparative Example 29: Example 29 was repeated except that the aromatic copolyamideimide in Example 29 was replaced with the aromatic copolyamideimide in Synthesis Example 29. The results are shown in Table 9. Example 30: Twenty (20) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 23, 30 % by weight of PET, 10 % by weight of PC and further 40 % by weight of glass fibers were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The obtained pellets were injection-molded in the same manner as in Example 29 to form test pieces. The test pieces were measured for a heat deformation temperature, a flexural strength and further a melt flow value in the same manner as in Example 29. The results are shown in Table 9. Comparative Example 30: Example 30 was repeated except that the aromatic copolyamideimide in Example 30 was replaced with the aromatic copolyamideimide in Synthesis Example 29. The results are shown in Table 9. Example 31: Thirty (30) percent by weight of the aromatic copolyamideimide produced in Synthesis Example 23, 30 % by weight of PBT and 40 % by weight of glass fibers were melt-kneaded at 280°C and pelletized with a twin-screw extruder. The obtained pellets were injection-molded in the same manner as in Example 29 to form test pieces. The test pieces were measured for a heat deformation temperature, a flexural strength and further a melt flow value in the same manner as in Example 29. The results are shown in Table 9. Comparative Example 31: Example 31 was repeated except that the aromatic copolyamideimide in Example 31 was replaced with the aromatic copolyamideimide in Synthesis Example 29. The results are shown in Table 9. Example 32: Example 11 was repeated except that PBT was replaced with PET. The results are shown in Table 9. Examples 33 and 34: Example 32 was repeated except that the aromatic copolyamideimide in Example 32 was replaced with the aromatic copolyamideimides in Synthesis Examples 24 and 25. The results are shown in Table 9. Comparative Example 32: Example 32 was repeated except that the aromatic copolyamideimide in Example 32 was replaced with the aromatic copolyamideimide in Synthesis Example 29. The results are shown in Table 9. Synthesis Example Composition of acid components Diisocyanate TDI (mole%) Glass transition point (°C) TMA (mole%) / IPA (mole%) / ADA (mole%) 21 20/25/ 5 50 280 22 (20/25/ 5) (acid chloride) (50) (m-TDA) 280 23 20/20/10 50 250 24 20/10/20 50 230 25 12.5/30/7.5 50 280 26 5/35/10 50 280 27 30/15/ 5 50 295 28 40/ 5/ 5 50 305 29 50/ 0 /0 50 326 30 0/50/ 0 50 260 31 0/ 0/50 50 155 TMA; trimellitic anhydride IPA; isophthalic acid ADA; adipic acid TDI; 2,4-toluylene diisocyanate m-TDA; m-toluylenediamine acid chloride; anhydrous trimellitic acid chloride/isophthalic acid dichloride/adipic dichloride Kind of amideimide (wt.%) Kind of polyester (wt.%) Heat deformation temp. (°C) Flexural strength (MPa) Melt-flow value (cc/sec) Ex. 21 Synthesis Example 21 50 PBT 50 200 93 0.08 Ex. 22 Synthesis Example 22 50 PBT 50 197 100 0.09 Ex. 23 Synthesis Example 23 50 PBT 50 203 98 0.07 Ex. 24 Synthesis Example 24 50 PBT 50 200 90 0.08 Ex. 25 Synthesis Example 25 50 PBT 50 204 98 0.10 Ex. 26 Synthesis Example 26 50 PBT 50 190 85 0.08 Ex. 27 Synthesis Example 27 50 PBT 50 184 82 0.09 Ex. 28 Synthesis Example 28 50 PBT 50 180 73 0.09 Comp. Ex. 21 Synthesis Example 29 50 PBT 50 180 48 0.13 Comp. Ex. 22 Synthesis Example 30 50 PBT 50 192 43 0.11 Comp. Ex. 23 Synthesis Example 31 50 PBT 50 159 38 0.09 Kind of amideimide (wt.%) Kind of other component(s (wt.%) Kind of polyester (wt.% Heat deformation temp. (°C) Flexural strength (MPa) Melt-flow value (cc/sec) Ex. 29 Synthesis Example 23 40 PBT 50 PC 10 175 100 0.20 Ex. 30 Synthesis Example 23 20 PET 30 PC/GF 10/40 221 180 0.23 Ex. 31 Synthesis Example 23 30 PBT 30 GF 40 220 160 0.18 Ex. 32 Synthesis Example 23 30 PET 30 GF 40 230 190 0.30 Ex. 33 Synthesis Example 24 30 PET 30 GF 40 230 180 0.30 Ex. 34 Synthesis Examle 25 30 PET 30 GF 40 233 180 0.30 Comp. Ex. 29 Synthesis Example 29 40 PBT 50 PC 10 163 84 0.22 Comp. Ex. 30 Synthesis Example 29 20 PET 30 PC/GF 10/40 203 130 0.25 Comp. Ex. 31 Synthesis Example 29 30 PBT 30 GF 40 205 120 0.19 Comp. Ex. 32 Synthesis Example 29 30 PET 30 GF 40 210 140 0.32

Claims: A resin composition which comprises: (A) an aromatic copolyamideimide containing (i) 5 to 95 mol% of a recurring unit represented by the formula (1) and (ii) 5 to 95 mol% of the total of a recurring unit represented by the formula (2) and/or a recurring unit represented by the formula (3), provided that the total amount of these three recurring units is 100 mol%, wherein Ar in the formula (1) denotes a trivalent aromatic group containing at least one 6-membered carbon ring, Ar 1 in the formula (2) denotes a divalent aromatic group containing at least one 6-membered carbon ring, R 1 in the formula (3) denotes a divalent aliphatic group, and R in the formulas (1), (2) and (3) denotes a divalent aromatic or aliphatic group, and (B) a polyester resin which is a crystlline aromatic polyester obtainable from an aromatic dicarboxylic acid or a derivative thereof and a dihydric alcohol as raw materials, the weight ratio of the aromatic copolyamideimide (A) and the polyester resin (B) ((A)/(B)) being 95/5 to 5/95; the aromatic copolyamideimide (A) being prepared by polymerizing an aromatic tricarboxylic acid anhydride and at least one of an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid with a diisocyanate compound in a plurality of steps such that in the first step the polymerization reaction is conducted in a temperature range of 50 to 110°C and in the second and any subsequent steps the polymerization reaction is conducted in a temperature range of higher than 110°C but not higher than 200°C; and the aromatic copolyamideimide (A) having a reduced viscosity (measured in a dimethylformamide solvent at 30°C in a concentration of 1g/dl) of 0.1 to 1.0 dl/g. The resin composition of claim 1, wherein the amount of the recurring unit represented by the formula (1), which is contained in the aromatic copolyamideimide (A), is 10 to 70 mol% when the total amount of the above three recurring units is 100 mol%. The resin composition of claim 2, wherein the amount of the recurring unit represented by the formula (1), which is contained in the aromatic copolyamideimide (A), is 10 to 50 mol%. The resin composition of claim 1, wherein the aromatic copolyamideimide (A) has a reduced viscosity (measured in a dimethylformamide solvent at 30°C in a concentration of 1 g/dl) of 0.2 to 0.7 dl/g. The resin composition of claim 1, wherein the aromatic copolyamideimide (A) is obtainable by a polymerization reaction conducted in two or three steps. The resin composition of claim 5, copolyamideimide (A) is obtainable by a polymerization reaction wherein the temperature is set at 50 to 110°C in the first step to terminate formation of an amide group, and is conducted in the subsequent steps at a temperature which is 20 to 80°C higher than the temperature in the first step. The resin composition of claim 1, wherein the polyester resin is a polyalkylene terephthalate or a polyalkylene-2,6-naphthalenedicarboxylate. The resin composition of claim 1, wherein the weight ratio of the aromatic copolyamideimide (A) and the polyester resin (B) ((A)/(B)) is 10/90 to 70/30. A process for preparing a resin composition which comprises preparing an aromatic copolyamideimide (A) having a reduced viscosity (measured in DMF solvent at 30°C in a concentration of 1g/dl) of 0.1 to 1.0 dl/g, containing 5 to 95 mol% of a recurring unit represented by the formula (1) and 5 to 95 mol% of at least any one of a recurring unit represented by the formula (2) and a recurring unit represented by the formula (3), provided that the total amount of these three recurring units is 100 mol%, wherein Ar in the formula (1) denotes a trivalent aromatic group containing at least one 6-membered carbon ring, Ar 1 in the formula (2) denotes a divalent aromatic group containing at least one 6-membered carbon ring, R 1 in the formula (3) denotes a divalent aliphatic group, and R in the formulas (1), (2) and (3) denotes a divalent aromatic or aliphatic group, by polymerizing an aromatic tricarboxylic acid anhydride and at least one of an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid with a diisocyanate compound in a plurality of steps such that in the first step the polymerization reaction is conducted in a temperature range of 50 to 110°C and in the second and any subsequent steps the polymerization reaction is conducted in a temperature range of higher than 110°C but not higher than 200°C; and forming a resin composition comprising the thus produced aromatic copolyamideimide (A) with (B) a polyester resin, which is a crystalline aromatic polyester obtainable from an aromatic dicarboxylic acid or a derivative thereof and a dihydric alcohol as raw materials the weight ratio (A)/(B) being 95/5 to 5/95.

Inventors: AMAGAI AKIKAZU, BAN HAJIME, HARADA HIDEFUMI, KAWAKI TAKAO, TAKEDA YUJI, YAMADA TOSHIAKI, YAMAMOTO KOJI, AMAGAI, AKIKAZU, BAN, HAJIME, HARADA, HIDEFUMI, KAWAKI, TAKAO, TAKEDA, YUJI, YAMADA, TOSHIAKI, YAMAMOTO, KOJI, AMAGAI, AKIKAZU, CORPORATE RESEARCH LABORATORY,, BAN, HAJIME, CORPORATE RESEARCH LABORATORY,, HARADA, HIDEFUMI, CORPORATE RESEARCH LABORATORY,, KAWAKI, TAKAO, CORPORATE RESEARCH LABORATORY,, TAKEDA, YUJI, CORPORATE RESEARCH LABORATORY,, YAMADA, TOSHIAKI, CORPORATE RESEARCH LABORATORY,, YAMAMOTO, KOJI, PLASTICS CENTER OF MITSUBISHI GAS
Applicants: MITSUBISHI GAS CHEMICAL CO, MITSUBISHI GAS CHEMICAL COMPANY, INC.
Application year: 1994
Main classification: C08L79
IPC codes: C08L79, C08L67, C08L81